Variable speed transmission



Aug. 9, 1938. w. P. SCHMITTER VARIABLE SPEED TRANSMISSION Filed Jan. 18, 1937 2 Sheets-Sheet l INVENTOR. Walter R Schmz'fler A TTORNEY.

Aug. 9, 1938. w. P. SCHMITTER VARIABLE SPEED TRANSMISSION Filed Jan. 18, 1937 2 Sheets-Sheet 2 INVENTOR: WalzerR ichmiitr A TTORNEY.

i Patented Aug. 9, 1938 VARIABLE SPEED TRANSMISSION Walter P. Schmittcr, Milwaukee, Wis., assignor a The Falk Corporation, Milwaukee, Wis., a corporation of Wisconsin Application January 18, 1937, Serial No. 121,119

15 Claims.

This invention relates to variable speed transmissions of the type involving a set of inclined tapered planet rollers and a contact ring adjustable lengthwise thereof to regulate their planetary action.

A variable speed transmission of this type,

which has proven commercially successful, is disclosed in the copending application of myself and Alfred G. Bade, Serial No. 52,095, filed November 29, 1935. In the transmission therein disclosed, the control element is in the form of a ring which encircles and contacts the rollers, the required contact pressure between the rollers and ring being maintained by a pressure inducing device which functions to force the rollers along their outwardly inclined axes. This resultsin a peculiar reaction between the rollers and ring, which limits the degree of contact pressures thus obtained and which prevents automatic reduction of those pressures as the load on the transmission decreases, so that when operating at light loads the contact pressures are unnecessarily high,

subjecting the transmission and tear. 25 One object of the present invention is to provide, in a transmission of the character mentioned, a novel combination and arrangement of parts which'will render the contact pressure between the rollers and the contact element automatically responsive to the torque load on the transmission. This I accomplish by utilizing the reactive force of the rollers upon the contact ring, to force the rollers outwardly against the ring.

Another object is to provide an improved means for developing the required contact pressures.

Another object. is to provide a 'novel combination and arrangement of parts which will simplify the transmission and facilitate assembly.

Other objects and advantages will appear, either expressed or implied, from the following description of an illustrative embodiment of the present invention.

In the accompanying drawings:

Figure 1 is a longitudinal sectional view of a variable speed transmission embodying the present invention.

to unnecessary wear Fig. 2 is atransverse sectional view along the line 2-4 of Fig. 1.

Fig. 3 is a. fragmentary view along the line 3-3 of Fig. 2 showing the method of mounting the control ring. a e I Fig. 4 is a fragmentary view along the line 4-4 of Fig. 1.

The variable speed transmission shown in the drawings is somewhat similar to that described in the application identified above. It is contained in a housing l0, closed at one end and having a head It by which the other end may be closed. A driven shaft l 2 is journalled in bearings it and a M in one end of the housing. A drive shaft i5 aligned with the driven shaft I2 is journalled in a bearing iii in the head II at the opposite end of the housing and in a bearing ll mounted in a head [8 fixed on the end of the driven shaft I2. 10

Surrounding the drive shaft l5 within the housing ill is a rotor l9 comprising a disk or head and a second disk or head 2! rigidly connected by cross bars 22 preferably T-shaped in cross section. The head 20 is mounted upon a bearing 16 23 seated upon a tubular hub portion 24 of a cage 25 which is fixed to and projects inwardly from the head Ii of the housing around the bearing I6 of the drive Shaft. The head 2| is likewise. mounted upon a bearing 26 upon the drive shaft 20 i5 near its opposite end. The rotor I 9- is thus freely rotatable about the common axes of the shafts I2 and i5.

Carried by the rotor i9 is a set of tapered planetary rollers 21 in any convenient number; three 25 such rollers as shown in the drawings have been known to produce satisfactory results. These tapered rollers 2'! are mounted in an inclined position so that their outer edges normally are substantially parallel to the axes of the shafts I2 80 and I5, and so that the axes of the rollers, if extended, would meet at a common apex on the extended axes of the shafts l2 and I5.

' Each of the tapered rollers 21 is mounted at its smaller end in the head 20- of the rotor I 8 by means of a spherical or self-aligning bearing 23 of a well known type, which provides a fixed fulcrum for that end of the roller permitting angular displacement of the roller relative to the fixed central axis.

The opposite or large end of each of the rollers 21 is journalled by means of a bearing 29 in a slide block 30 guided in a radial slot 30' formed in the head 2| of the other end of the rotor l9. By this means the rollers 21 are secured to rotate with the rotor l9, but are free at one end to move radially outward from the central axis of i the rotor.

Upon the end of each of the rollers 21 is fixed a pinion gear 3i. These pinions3| together con stitute a set of planet gears which engage with and revolve about a sun gear 32 fixed to the drive shaft I5. The planet pinions 3| also are engaged with an internally toothed ring gear33 mounted upon a disk 34 fixed to the head l8 of the driven shaft II. The internal gear 33, the planet pinions 3| and the sun gear 32 are preferably so formed as to provide excess clearance at the bases of their teeth so as to permit slight outward. movement of the rollers 21 and their pinions 3| without objectionable interference.

The rollers 21 and the pinions 3| are rotated about their axes by engagement of the pinions with the sun gear 32 upon the drive shaft l5. From this rotary motion planetary movement of the rollers about the drive shaft I5 is induced by rolling contact of the rollers with a control ring 35. The control ring encircles and contacts all. of the rollers 21, and by movement along the rollers axially of the rotor l3, serves to regulate and govern the planetary action of the rollers. This axial movement of the control ring 35 is effected by a nut 31 bifurcated to receive the periphery of the ring and carried by and in screw threaded engagement with a screwrod 33 journalled in the housing Ill and extending lengthwise of the rollers.

In order that the gripping contact of the rollers against the control ring 35 may automatically respond to the torque load on the transmission, the rotary drag of the rollers against the control'ring is translated into an outward thrust tending to press the rollers more firmly into contact with the control ring. For this purpose the control ring 35, which floats freely around the rollers 21, is restrained from rotation with the rollers solely by either of two lugs 39 fixed to and projecting radially from the ring. These lugs 33 confine between them a fin 40 projecting from a rock shaft 4| journalled in the housing It. Near the end of the shaft 41 is fixed a lug 42 bifurcated to receive the end of a lever 44 fixed to and projecting outwardly from a rockable thrust member 45 situated within the cage 25, the lever 44 projecting through a slot 45 in the cage 25. By means of a bearing 41 the member 45 is mounted upon the drive shaft l5, which may nevertheless rotate freely within it.

By this system of levers, the rotary impulse of the control ring 35, produced by the drag of the rollers 21, is transmitted through the fin 40,

the rock shaft 4|, the lug 42 and the lever 44, and tends to turn the member 45 about the axis of the shaft 5.

Surrounding the member 45 adjacent the housing II is a ring 43 keyed to the member 45, and which has formed on its outer face a series of shallow radial grooves 49, having inclined sides 50. A similar stationary ring 5| is affixed to the head ll of the housing opposite the ring 48 and has similar grooves 52 situated opposite the grooves 49, and having inclined sides 53. Betweenthe rings 43 and 5| is a cage 54 loosely surrounding the shaft l5, and serving as a carrier for a series of balls 55 corresponding to and fitting into the grooves 49 and 52. By such an arrangement, the tendency of the ring 45 to rotate will result in wedging the balls 55 between the cam surfaces provided by the inclined sides of the opposing grooves, thus translating the rotary motif 1 o the member 45 into an axial thrust.

This axial thrust is carried by a sleeve 55 extending from the member 45 and surrounding the shaft 5, and is transmitted to an internal\ ring 51 contacting the rollers 21 near their large ends. The ring 51 surrounds the shaft I5 and is mounted thereon by a bearing 53. Between the ring 51 and the sleeve 55 is interposed a thrust bearing 53 and a second sleeve surrounding the sleeve 53 and in screw'threaded engagement therewith to permit an initial adjustment of the effective length of the sleeve 56. The contact surface 5| between the ring 51 and the thrust bearing 59 is preferably of spherical form in order to distribute the thrust over the ring 51.

Through the arrangement noted, axial thrust on the sleeve 56 results in wedging the ring 51 against the rollers 21, and thus forces the free ends of the rollers 21 radially outward from the central axis against the control ring35. The rotary drag of the rollers 21 against the control ring 35 is thus translated to induce outward pressure of the rollers 21 against the control ring. Since the rotary drag of the rollers 21 against the ring 35- will increase. as the torque upon the rollers increases, an initial gripping contact being presumed, the mechanism will thus operate to increase the pressure of the rollers against the ring in response to such increase in torque.

Because the internal ring 51 presses upon the rollers 21 near their free ends opposite the ful-' crum provided bythe self-aligning bearing 28, the rollers 21 themselves will have a lever action, so that a constant end thrust upon the sleeve 56 will produce greater pressure between the rollers' 21 and the control ring 35 when the control ring is near the fulcrum bearing 28 than when it is near the opposite end of the rollers. To com-1 pensate for this discrepancy, provision is made. for increasing the end thrust on the sleeve 56 as the control ring 35 nears the large end of the roll-f ers. In this instance this is accomplished by cutting the fin 40 on a bias, as shown in Fig. l, and forming a flange 52 along its inclined edge.. The lugs 39 will thus engage the flange 62 at varying distances outward from the axis of the rock shaft 4|, depending upon the axial position of the control ring 35. Thus when the control ring 35 is near the large end of the rollers, the greater leverage of the fin 40 will induce a greater thrust upon the sleeve 56 and the internal ring 51;

As may be seen from 'the drawings, the control: ring 35 has been mounted around the rollers 21 in such fashion that it floats freely in every direction radially of the axis of the shaft l5. It may thus compensate for any inequalities in the adjustment of the rollers 21, and serves to distribute and equalize the pressures between the ring and the rollers 21.

It is of course understood that power will be transmitted through this transmission in a manner similar to that of the application above identi-' fled. Rotation of the drive shaft l5 and the sun gear 32 causes the pinions 3| and the rollers 21 to revolve on their axes and to partake of a plane tary movement around the drive shaft i5. This planetary motion is induced and governed by rolling contact of the rollers 21 against the control ring 35. The combined rotary and planetary. movement of the pinions 3| is transmitted through the ring gear 33 to cause rotation of the, driven shaft l2. Since the planetary action of. the rollers 21 varies as the control ring 35 is shifted axially of the transmission, the speed of the driven shaft i2 will thus be varied correspondingly, while the speed of the driving shaft l5 remains constant.

Various changes may be made in the embodiments of the invention hereinabove specifically described without departing from or sacrificing the advantages of the invention as defined in theappended claims.

I claim:--

1. In a variable speed transmission, the combination of a rotor, an inclined tapered planet roller rotatable with and with respect to said rotor, a rigid control member contacting said I roller, means including said rotor for mounting said member and roller for movement relative to one another in a direction lengthwise of said roller to regulate the speed ratio of the transmission, saidroller reacting on said member to impose a torque load on the latter, and means resisting. the torque load on said member and reacting on said roller to develop contact pressures between said roller and member.

2. In a variable speed transmission, the combination of a rotor, an inclined tapered planet roller rotatable with and with respect to said rotor, a circular control member contacting said roller, means including said rotor for mounting said member and roller for movement relative to one another in a direction lengthwise of said roller, said roller reacting on said member to impose a torque load thereon, and means resisting the torque load on said member and reacting on said roller to force said roller against said member to develop pressure contact therebetween.

3. In a variable speed transmission, the combination of a plurality of tapered relatively inclined planetary rollers, rotary carrier means therefor, a rigid control ring encircling and contacting said rollers and moveable lengthwise thereof to regulate their motion, means restraining said ring against rotation, and means responsive to the reaction between said ring and said restraining means for developing contact pressures between said rollers and ring.

4. In a variable speed transmission, the combination of a rotor, a plurality of inclined tapered planet rollers rotatable with and with respect to said rotor, a circular control member, means including said rotor for mountingsaid member and rollers for movement relative to one another in directions both lengthwise and transversely of said rollers, means for effecting said relative lengthwise movement to regulate the speed ratio of the transmission, means for effecting said transverse movement to develop pressure contact between said rollers and said member, said rollers reacting on said member to impose a torque load thereon, and means for transmitting the torque load on said member to said last named means to energize the latter.

5. In a variable speed transmission, the combination of a group of tapered planetary rollers mounted to revolve about a common central axis and to rotate about their individual axes inclined relative to the central axis, control means encircling and contacting said group of rollers and moveable lengthwise thereof, means disposed concentrically of said group of rollers and moveable lengthwise of said rollers to force the latter outwardly against said control means, and means responsive to the torque load on said transmission for actuating said last named means.

6. In a variable speed transmission, the combination of a group of tapered relatively inclined rollers mounted for planetary movement about a common central axis, control means encircling and contacting said rollers and moveable lengthwise thereof, a member moveable along said axis to force saidrollers into pressure contact with said control means, and means energized by the torque load on said control means for actuating said member.

71in a variable speed transmission, the combination ,of a group of tapered relatively inclined rollers mounted for planetary movement about a common central axis, control means encircling and contacting said rollers and moveable lengthwise thereof, a member moveable axially of said roller group to expand the latter against said encircling means, and means including a member rockable in response to the torque load on said encircling means for actuating said axially moveable member.

, ing a member rockable in response to the torque load on said encircling means for actuating said moveable means.

9. In a variable speed transmission, the combination of a group of tapered relatively inclined rollers mounted for planetary movement, control means encircling and contacting said rollers and moveable lengthwise thereof to control their motion, means including a rock shaft for restraining said control means against rotating, and means energized by the torque load on said rock shaft for developing contact pressures between said rollers and said control means.

10. In a variable speed transmission, the combination of a group of tapered relatively inclined rollers mounted for planetary movement, control means encircling and contacting said rollers and axially moveable lengthwise thereof to regulate their motion, means for inducing pressure contact between said rollers and control means, a rock shaft energized by the torque load on said control means for energizing said last named means, and means coacting with said rock shaft and said control means for automatically varying the eifect of said torque load on said pressure inducing means in accordance with changes in the axial position of said control means on said rollers.

11. In a variable speed transmission, the combination of a plurality of tapered relatively inclined rollers mounted for planetary movement, control means encircling and contacting said rollers and axially moveable lengthwise thereof, means energized by the torque load on said control means for inducing pressure contact between said rollers and said control means, and means forvarying the eifect of, said torque load on said pressure inducing means in accordance with changes in the axial position of said control means on said rollers.

12. In a variable speed transmission, the combination of a plurality of tapered relatively inclined rollers mounted for planetary movement, a floating control ring encircling and contacting said rollers, means for shifting said ring lengthwise of said rollers to regulate their motion, and means separately engaged with said ring for restraining said ring against rotation.

13. In a variable speed transmission, the combination of a plurality of tapered relatively ini named means for inducing pressure contact between said rollers and ring.

1 4. In a variable speed transmission, thecombination of a plurality of tapered relatively inclined rollers mounted for planetary movement,

a floating control ring encircling and contacting said rollers, a ring actuator moveable to shift the latter axially lengthwise oi said rollers, and means extending lengthwise of said rollers and separately engaged with said ring in all axial posi- 10 clined rollers mounted for planetary movement,

a radially displaceable control ring encircling and contacting said rollers, ring actuating means effective to shift said ring lengthwise of said rollers without interfering with free rotation or radial displacement of said ring, and additional means separately engaged with said ring and effective to restrain said ring against rotation without interfering with free axial or radial displacement of said ring.

WALTER P. SCHMI'I'I'ER. 

